1. Field of the Invention
The invention relates to rim construction for an inflatable tire and to a method of mounting an inflatable tire on an improved tire rim structure.
2. Prior Art
The prior art utilizes a wheel rim base with a one piece circular band thereabout. The circular band is normally held in place relative to the rim base by use of a lock ring. A serious problem has existed with such prior art devices in that if the lock ring is not properly seated in its groove prior to inflation of the tire, the tire as it expands can throw parts of the apparatus outwardly. Also, circumferential cracks can develop in the groove for the lock ring thus presenting a safety problem as well as causing scrapping of expensive parts. A butt weld is normally utilized in the prior art construction in the band. Failure of this weld can occur due to shock and fatigue loading experienced in tire and rim combinations on the wheels of an operating vehicle. This creates a chronic problem not only with respect to early scrappage of the parts but also in many cases a problem of blowing out of the tire as it loses pressure through such cracks. In the prior art structure a so-called driver is used to drive the band from the wheel-rim base. This driver is not always able to stop the slippage between the band and the wheel base and can itself fail. This is a particularly bad problem with larger tires, with new parts and with steel radial tires. Once the driver twists out, a crack may develop across the band from the fracture area thus causing a loss of pressure and a subsequent tire blow out. Yet another problem is corrosion of the seat upon the band on which the tire bead sits due to condensed moisture. In this problem the tire bead tends to freeze in its mounted position thus making removal of the bead difficult when it is necessary to demount the tire. In some cases, such demounting becomes actually impossible without some damage to the tire, the wheel-rim base, the band, or the tooling used. Still further, the prior art makes use of a sealing O-ring compressed between the band and the wheel-rim base and problems can occur with this O-ring during mounting, especially at the gap between the ends of the lock ring. Still further, the wedging action of the tire bead as it moves out on the bead seat can contribute to the problem of demounting.